Independently and not as an agent of the Government the contractor shall furnish qualified personnel as needed to provide gastroenterology medical services, as specified below: A. Perform medical examinations and evaluations. B. Perform diagnostic and therapeutic endoscopic services. C. Perform high risk procedures and monitoring. D. Provide emergencies call back services. The contractor shall provide eighty (80) of senior gastroenterology services each week (7 day period) at the director of the Project Officer. Normal service will require one or two residents Monday through Friday; however, weekend and holiday coverage (other than emergency call back) may be required dependent upon patient care needs. Call back service will be required evenings, nights and on weekends and holidays and at any other time a senior resident is not available at the Clinical Center.